The use of catalysts in the processing of hydrocarbons is well known. Catalysts enable hydrocarbon processing reactions, such as hydro-treating, hydrocracking, steam cracking or upgrading reactions, to proceed more efficiently under various reaction conditions with the result that the overall efficiency and economics of a process are enhanced. Different catalysts are more effective in certain reactions than others and, as a result, significant research is conducted into the design of catalysts in order to continue to improve the efficiencies of reactions. Many factors such as catalyst chemistry, particle size, support structure and the reaction chemistry to produce the catalyst are very important in determining the reaction efficiency and effectiveness as well as the economics of a particular catalyst.
Catalysts can be generally categorized as supported and unsupported catalysts. Supported catalysts are more widely used due to several advantages including the high surface area available to anchor active phases (usually metals) predominantly responsible for the catalytic activity on the support. One advantage of supported catalysts over unsupported catalysts is that no separation of catalysts from reactants and products is required from within or outside the reaction vessel.
While effective in many applications, supported catalysts are at a disadvantage when used with feedstocks that inevitably produce solid deposits within the porous network of the catalyst support. In such cases a progressive loss of catalyst performance due to pore plugging occurs, making larger quantities of catalysts required for a given process to maintain efficient reactions.
Unsupported catalysts are not physically supported on a solid matrix and therefore are less expensive to produce. In reactions where unsupported catalysts are soluble in the reaction media, difficulties in recovery of the catalysts from the product stream increase reaction or production costs because the catalysts must be replaced. There may also be a requirement for the reactants to be subjected to costly separation processes. Frequently, unsupported metal based catalysts with equivalent particle sizes or diameters to supported catalysts offer lower surface area of catalytic active phases. However, unsupported catalysts with particle sizes below the micron range provide advantages over supported catalysts by increasing the surface area available of active sites for reaction and thus, may enable a reaction to proceed more efficiently as compared to a reaction utilizing a supported catalyst.
While there is no universal rule with respect to the superiority of one class of catalyst over another, in many systems, a primary consideration in choosing or designing a catalyst system is the potential trade-off between the reaction efficiency and costs of unsupported catalysts versus supported catalysts.
In situ upgrading of hydrocarbons directly in a reservoir has become more feasible with development of processes using a high heating capacity fluid extracted from the same produced crude oil. This heating fluid may also be used as the heat conductor for the nano-catalyst which is needed to promote the upgrading reactions at relatively low temperatures.
The option of using conventional (heterogeneous) upgrading catalysts, to process heavy crude oil produced in a reservoir or very close to the producing well has been investigated. One of the most significant improvements in this area has led to the possibility of applying the process well to well, and, as a result, smaller scale equipment can be used which will resist pressure. Because the upgrading reactions occur within the reservoir, the small amount of coke that could be produced would remain within the reservoir (Weissman, J. G. and R. V. Kessler, Downhole heavy crude oil hydroprocessing. Applied Catalysis A: General, 1996. 140(1): p. 1-16, incorporated herein by reference in entirety).
Catalytic upgrading near the producing well has been investigated in an upgrading process which includes placing a catalyst in the producing well through conventional injection techniques and heating the production zone using electric elements, and injecting hydrogen or synthesis gas in the producing well. In this way, the fluids coming from the in situ combustion are forced to pass through the reservoir matrix. Results from various experiments indicated a larger production of hydrogen and hydrocarbons in the case of the catalytic test in comparison with the non-catalytic test. An increase of 8 degrees API was also observed in the density of the catalytic product, and a reduction of around 50% m of sulfur (Weissman, J. et al., Down-hole catalytic upgrading of heavy crude oil. Energy & Fuels, 1996. 10(4): p. 883-889, incorporated herein by reference in entirety). However, the risk of contact between fluids from in situ combustion and synthesis gas or hydrogen at a high temperature is an important challenge for the control of that process.
The abovementioned investigations did not provide solutions to major challenges of a real-world upgrading process. The problem of incorporating a catalyst through the porous media of the reservoir in conditions different to those of air injection, and avoiding the deactivation of the catalyst was not addressed. This last challenge involves the maintenance of an economic process while reducing coke formation that at the same time is the cause and consequence of catalyst deactivation.
As such, one of the existing main challenges is the rapid deactivation or poisoning of the catalyst due to the large amount of contaminants such as: asphaltenes, sulfur and metals (Galarraga, C. E. and P. Pereira-Almao, Hydrocracking of Athabasca bitumen using submicronic multimetallic catalysts at near in-reservoir conditions. Energy & Fuels, 2010, 24(4): p. 2383-2389, incorporated herein by reference in entirety). Another challenge involves the transport of heat to the reservoir in a conventional (non-electrical) and continuous manner, without incurring large costs of energy transfer and while ensuring production with a stable increase in quality and crude oil. In situ combustion produces upgraded products only at the end of its lifetime. At the same time, this process produces olefins in significant amounts when insufficient levels of hydrogen are present.
Hydrocracking of bitumen using a variety of ultra-dispersed catalysts based on metallic particles (nickel, cobalt, tungsten and molybdenum) nano or sub-micron particles has been described (U.S. Pat. Nos. 8,551,907, 8,304,363, 8,298,982, 8,283,279, and 7,897,537 each of which is incorporated herein by reference in entirety).
These ultra-dispersed catalysts have been investigated under conditions similar to the conditions existing in the reservoirs of the Athabasca region of Alberta, Canada, with sand packing within a permeability range between about 1 to about 12 Darcies. The tests performed (with or without catalysts) were between about 270° C. and about 380° C. and between about 8 and about 210 hours for crude oil. With the catalyst contact and the hydrogen flowing continuously, it was confirmed that the ultra-dispersed catalysts increase conversion, reduce micro carbon residue, reduce coke formation, and increase desulfurization. It was also confirmed that upon increasing temperature, the conversion of the residue fraction of the crude oil increases and the quality of the hydrocarbon product is reproducibly improved in terms of density, viscosity, and sulfur levels (Luis Alejandro Coy, P. P.-A. Experimental Reactive Simulation of a Hot Fluid Injection Process for In-Reservoir Upgrading. In World Heavy Oil congress 2014. New Orleans, La., USA: DMG Energy Conferences; Galarraga, C. E. and P. Pereira-Almao, Hydrocracking of Athabasca bitumen using submicronic multimetallic catalysts at near in-reservoir conditions. Energy & Fuels, 2010. 24(4): p. 2383-2389; Rendon, V., Experimental Evaluation of In Situ Upgrading by Continuous Injection of Submicronic Catalysts at Moderate Temperatures with Hydrogen Addition, in Schulich School of Engineering. 2011, University of Calgary: Calgary. p. 238, each of which is incorporated herein by reference in entirety).
The transportability of ultra-dispersed catalysts in vacuum gas oil (VGO) initially at a temperature close to 25° C. has been described. Most notably, the surfactant that could be used in the preparation of the ultra-dispersed catalysts does not decompose entirely under the tested conditions, and that it had a tendency to form emulsions within a packed bed (previously saturated with water), precipitating some particles causing blocking of the packing, especially at its entrance. In a later test studying the effect of formation water, it was found that retention of the catalyst at the surface of the sand is slightly higher (approx. 18%) than the injected amount, given the absence of water at the surface of the sand grains. It was also found that the metallic particles suspended in the fluid, within the packing, were dragged out of the system, whereas those previously retained in the bed were not significantly affected. Further experiments at higher temperature show that the flow of a hydrocarbon stream with nano-dispersed catalysts can easily propagate through a packed bed without negatively affecting the permeability of the packed bed (Zamani, A., B. Maini, and P. Pereira-Almao, Experimental study on transport of ultra-dispersed catalyst particles in porous media. Energy & Fuels, 2010. 24(9): p. 4980-4988; Zamani, A., B. Maini, and P. Pereira-Almao, Flow of nanodispersed catalyst particles through porous media: Effect of permeability and temperature. The Canadian Journal of Chemical Engineering, 2012, 90(2): p. 304-314, each of which is incorporated herein by reference in entirety).
Tests at higher temperature (150° C.) with low concentration of ultra dispersed catalysts showed retention of the catalyst of at least 20%. At higher temperature 280° C. or more no evidence of the catalyst at the exit of the packing was found. Thus retention is increased at high temperatures of at least 150° C. It is possible that hydrodemetalation reactions could be taking place at the highest temperatures indicated. Permeability reduction in the highest temperature tests was 5 to 1.9 Darcies after the injection of over 60 porous volumes through the packing and submitting it to diverse reaction conditions, with and without nano catalysts (Rendón, V., Experimental Evaluation of In Situ Upgrading by Continuous Injection of Submicronic Catalysts at Moderate Temperatures with Hydrogen Addition, in Schulich School of Engineering. 2011, University of Calgary: Calgary. p. 238, incorporated herein by reference in entirety).
The result of these investigations indicate that it is possible to inject an emulsion made up of heavy hydrocarbons, hydrogen and ultra-dispersed catalysts into a reservoir without damaging the structure of the reservoir. Moreover, it was confirmed that it is possible to fill the packed bed with sub micron particles, and that once inside the reservoir, the packed bed turns into a “fixed bed” type reactor, which can improve hydrocarbon streams without further addition of catalysts by adding a small amount of hydrogen. One such example is found in Canadian patent 2,810,022, which is incorporated herein by reference in entirety.
With these recent advancements in hydrocarbon processing technology, it is now possible to develop systems for performing larger scale processing of hydrocarbons. As a result, a number of problems must be addressed to take full advantage of the technology. One such problem is a requirement for a catalyst preparation unit with sufficient flexibility to produce hydrocarbon processing catalysts efficiently and at relatively low cost.